The technical field of this invention is signal processing and, in particular, noise reduction in the transmission or storage of data signals, such as broadcast motion picture or television signals.
During transmission, data signals can be degraded by various causes, such as inhomogeneities in the transmission medium and electromagnetic interference. Such channel degradation includes, for example, noise and echos, and the degradation can be observed in both one-dimensional and two-dimensional signals. For example, in conventional television broadcast signals, channel degradation is often visually perceived as poor resolution, speckles or "ghost" images. Similar problems can also arise during the storage of data on magnetic media and the like where defects in the medium or electromagnetic interference likewise result in degradation of the stored data.
In the field of television broadcasting, in particular, there is considerable interest in "extended definition television" (EDTV) systems to reduce signal degradation, as well as enhance other television features. The goal of such EDTV systems is the production of a broadcast signal that can be received with negligible loss of quality on existing home equipment but when received on an advanced receiver can produce a picture with improved resolution, aspect ratio, or sound.
Conventionally, television broadcast signals in the United States are transmitted in accordance with the National Television Systems Committee (NTSC) standards. The NTSC code provides a format whereby motion pictures (i.e., sequences of still frames) can be broadcast and reconstructed in a receiver for display in rapid succession to the viewer. There is considerable interest in adding additional information to broadcast signals in a manner that would be compatible with the NTSC format and yet permit an advanced receiver to decode the additional information.
There exists a need for extended definition television systems which can combat noise and other channel degradation effects in the transmission of television signals to provide enhanced viewing for a receiver attuned to decode advanced noise suppressing information, while also permitting viewing with a standard receiver with minimal visual disturbances. Such an extended definition system would satisfy a long-felt need in the art.
Moreover, there exists a need for better data transmission and storage systems, generally, which can suppress transmission channel and storage medium-induced noise and signal degradation.